1. Technical Field
The present invention is related to a semiconductor package constructed by containing a wiring board and a semiconductor device having a semiconductor chip, and also, related to a manufacturing method thereof.
2. Related Art
Conventionally, semiconductor packages in which semiconductor devices are mounted on wiring boards are known in the field. FIG. 1 is a sectional view for partially exemplifying a conventional semiconductor package 300. Referring to FIG. 1, the semiconductor package 300 has a semiconductor device 400 and a wiring board 500. The semiconductor device 400 has a semiconductor chip 410 and connecting terminals 420.
The semiconductor chip 410 is a semiconductor chip in which a semiconductor integrated circuit (not shown) and electrode pads (not shown) are formed on a semiconductor substrate (not shown) which is made of silicon, or the like in a thin plate form, while the connecting terminals 420 are formed on the electrodes (not shown). As the connecting terminals 420, for instance, solder bumps, and the like may be employed.
The wiring board 500 has an insulating layer 530, a wiring layer 540, a solder resist layer 550, and pre-solder 570. In the wiring board 500, the wiring layer 540 is formed, and furthermore, the solder resist layer 550 having an opening portion 550x is formed on the insulating layer 530. The pre-solder 570 is formed on a portion of the wiring layer 540, which is exposed from the opening portion 550x. As the wiring layer 540, for example, Cu, and the like may be employed. As the insulating layer 530, for instance, an epoxy resin, and a material (glass epoxy) in which cloths made of glass fiber are contained in an epoxy resin may be employed.
The connecting terminals 420 of the semiconductor device 400 are electrically connected to the pre-solder 570 formed on the wiring layer 540 of the wiring board 500.    [Patent Publication 1] JP-A-2004-296488    [Patent Publication 2] JP-A-2008-153340
On one hand, for instance, in the case that glass epoxy is employed as the insulating layer 530, a thermal expansion coefficient of the glass epoxy is of the order of 18 ppm/° C. On the other hand, in such a case that as the semiconductor substrate (not shown) which constitutes the semiconductor chip 410, for example, silicon is employed, a thermal expansion coefficient of the silicon is of the order of 3 ppm/° C. Due to such a difference between the thermal expansion coefficients, there is a problem that when heat is applied to the semiconductor package 300, stresses are produced in joining portions (between connecting terminals 420 and pre-solder 570), and thus, cracks occur therein.